What is the correct formula for dilution of stock solutions?

The formula for dilution of stock solutions is given by the equation C1V1 = C2V2, where C1 represents the concentration of the stock solution, V1 is the volume of the stock solution used in the dilution, C2 is the concentration of the diluted solution, and V2 is the final volume of the diluted solution. This equation reflects the principle that the amount of solute remains constant before and after dilution, which can be derived from the definition of concentration (mass/volume).

When performing dilutions, it is crucial to understand that you are starting with a more concentrated solution (C1) and adding a certain volume (V1) to achieve a desired final concentration (C2) in a larger volume (V2). The equation ensures that the total amount of solute in the stock solution is equal to the total amount of solute in the diluted solution, maintaining the mass balance.

The other options do not represent the correct relationships as defined by the principles of dilution. They either misplace variables or do not encapsulate the conservation of mass concept essential to dilution calculations. Thus, option A effectively conveys the relationship between concentrations and volumes during the dilution process.